Sharing a plugin's feature?

I am looking to create a site where users can “subscribe” to different groups (in BuddyPress). Each group will have its own calendar (which only the admin of that group can edit), and individual users will be able to see one synchronized calendar with all of their groups events.

2 questions.

1. How can I have multiple groups use a calendar plugin (under 1 install of WP) individually?

2. How can I make the calendars synced for individual users?

Please let me know if you know of a plugin/way to do this.